1. Field of the Invention
The present invention relates to sheet paper feed apparatus for a typewriter, and more particularly relates to sheet paper feed apparatus including means for removing a single sheet of paper from a stack and feeding the same to the platen of the typewriter.
2. Description of the Prior Art
Shingling apparatus for separating sheets and feeding the same have been in existance for some time. For example, see U.S. Pat. No. 3,008,709 issued on Nov. 14, 1961 to Buslik. The use of such shingling apparatus has been varied but conventionally has been employed in conjunction with some normal force to remove either the topmost or bottom-most sheet from a stack of sheets of paper. Typical bottom sheet shingling apparatus is illustrated in IBM TECHNICAL DISCLOSURE BULLETIN, Vol. 21, No. 9, February 1979, pages 3538-3539 and 3540-3542; and U.S. Pat. No. 4,165,870, issued on Aug. 28, 1979 to John L. Fallon, et al. Typical top sheet shingling apparatus is illustrated in IBM TECHNICAL DISCLOSURE BULLETIN, Vol. 20, No. 12, May 1978, pages 5119-5120; and copending U.S. patent application, Ser. No. 053,462, filed June 29, 1979 by R. E. Hunt.
In feeding individual sheets of paper to the platen of a typewriter, it is particularly advantageous if the sheet feeder can distinguish a single sheet of paper and present that single sheet of paper without additional drive or feed rolls for insuring separation to the platen of the typewriter inasmuch as this complicates the apparatus.
In the prior art such sheet feed apparatus employed friction rollers or wheels having high surface friction characteristics relative to the friction between the sheets to be separated and fed. Typical of such prior art is U.S. Pat. No. 1,357,070 issued Oct. 26, 1920 to Thomas A. Matthews which included a roller that was polygonal or fluted to form ribs for better frictional contact with the sheets. Similarly U.S. Pat. No. 3,630,516 issued Dec. 28, 1971 to Byung S. Hong included a paddle wheel roller with blades made of an elastomeric material having high surface friction characteristics, such as gum rubber. Another type of prior art sheet feed apparatus employed a relatively large wheel having a plurality of smaller wheels mounted about its periphery on bearings. In this arrangement the surface of the smaller wheels was usually constructed of a material having a relatively high coefficient of friction. An example of this type of sheet feed apparatus is shown in IBM TECHNICAL DISCLOSURE BULLETIN, Vol. 20, No. 12, May 1978, pages 5119-5120 and copending U.S. patent application Ser. No. 053,462 filed June 29, 1979 by R. E. Hunt.
The sheet feed wheel (shingler wheel) used in each of the prior art paper feed devices is relatively inefficient and expensive due to frictional wear and distortion and complexity of design. These prior art shingler wheels were also relatively noisy in operation due to the many moving parts.
It is therefore an object of the present invention to provide a shingler wheel that is simple in construction, efficient to operate and inexpensive.